This promise follows well upon that of yesterday. We are evidently to be conformed to our covenant Head, not only in His being bruised in His heel but in His conquest of the evil one. Even under our feet is the old dragon to be bruised. The Roman believers were grieved with strife in the church; but their God was “the God of peace” and gave them rest of soul. The archenemy tripped up the feet of the unwary and deceived the hearts of the simple; but he was to get the worst of it and to be trodden down by those whom he had troubled. This victory would not come to the people of God through their own skill or power; but God Himself would bruise Satan. Though it would be under their feet, yet the bruising would be of the Lord alone.
Let us bravely tread upon the tempter! Not only inferior spirits but the prince of darkness himself must go down before us. In unquestioning confidence in God let us look for speedy victory. “Shortly.” Happy word! Shortly we shall set our foot on the old serpent! What a joy to crush evil! What dishonor to Satan to have his head bruised by human feet! Let us by faith in Jesus tread the tempter down.

From Charles Spurgeon’s “Faith’s Checkbook”
The Bible’s First Promise
January 1
And I will put enmity between thee and the woman, and between thy seed and her seed; it shall bruise thy head, and thou shalt bruise his heel. (Genesis 3:15)

This is the first promise to fallen man. It contains the whole gospel and the essence of the covenant of grace. It has been in great measure fulfilled. The seed of the woman, even our Lord Jesus, was bruised in His heel, and a terrible bruising it was. How terrible will be the final bruising of the serpent’s head! This was virtually done when Jesus took away sin, vanquished death, and broke the power of Satan; but it awaits a still fuller accomplishment at our Lord’s second advent and in the Day of Judgment. To us the promise stands as a prophecy that we shall be afflicted by the powers of evil in our lower nature, and thus bruised in our heel; but we shall triumph in Christ, who sets His foot on the old serpent’s head. Throughout this year we may have to learn the first part of this promise by experience, through the temptations of the devil and the unkindness of the ungodly, who are his seed. They may so bruise us that we may limp with our sore heel; but let us grasp the second part of the text, and we shall not be dismayed. By faith let us rejoice that we shall still reign in Christ Jesus, the woman’s seed.